A younger brother finds himself forced into cross-dressing because his seemingly perfect older sister has a terrifying hidden past. The sister appears to be a model older sibling, a brilliant and capable woman who also has a brother complex. However, her true identity is that of a legendary former delinquent known as the Bloody Female Boss. The younger brother is dragged into her chaotic world, leading to a series of troublesome situations where he is made to wear women's clothing, have his clothes removed, and gets entangled in complicated relationships with people from her past and present. Eventually, an enemy who specifically targets the sister appears, forcing the brother into an even more precarious position as he tries to navigate this dangerous conflict. The story is set in a contemporary Japanese environment of school and family life, which is constantly disrupted by the sister's yankee (delinquent) history. No specific character names, detailed secondary characters, or distinct narrative arcs beyond the central premise and the appearance of a targeted enemy are available in the provided information.